As an additional note, I was reading an article a while ago that was similar to this, except it focused more on how survival is largely to do with the will of the mind. This is why people who are stranded in the desert or are seriously injured are able to survive longer than they were expected to. Even though their bodies may be giving out, their will power is what is keeping them going; they literally are keeping themselves alive when medically, they should be dead, by sheer willpower. It is incredible what the mind can do. The article also pointed out that this lines up with the statistic you mentioned, Abby, about people who are depressed being 40% more likely to develop heart failure. Even though their bodies were relatively healthy to begin with, the lack of will to carry on, coupled with the lifestyle that results from that mindset often lead to the body giving out.